1. Field of the Invention
The invention relates to a method of inspecting a wheel hub unit.
2. Description of the Related Art
In some wheel hub units, a hub wheel is fastened to a disc rotor and a wheel with bolts, and is rotatably attached to a vehicle body via a bearing.
In order to set a preload amount to a target value close to a preload of 0 (zero) after an axle is attached to a hub wheel (after an axial load is applied), a wheel hub unit as described above is shipped with the internal clearance of a bearing (rolling bearing that includes an inner ring, an outer ring, and rolling elements) set as a positive clearance (or a clearance between a negative clearance and a positive clearance). A “negative clearance” means an internal clearance of the rolling bearing in the case Where all the rolling elements of the rolling bearing roll between the inner ring and the outer ring. A “positive clearance” means an internal clearance of the rolling bearing in the case where the rolling elements of the rolling bearing slide between the inner ring and the outer ring.
Conventionally, a wheel hub unit of the above-described type is inspected by measuring the surface runout of a flange to which a wheel is attached, according to an inspection method using, for example, a dial gauge, at the time of shipment (see, for example, Japanese Patent Application Publication No. 2010-25796 (JP-2010-25796 A)).
With the aforementioned wheel hub unit including the bearing with a positive clearance, When an inspection object. which is a component of the wheel hub unit, is inspected an acoustic value and a flange surface runout are measured), a backlash may occur the bearing, resulting in a decrease in the reliability of inspection.